A high speed page width ink jet printer has recently been developed by the present applicant. This typically employs in the order of 51,200 ink jet nozzles to print on A4 size paper to provide photographic quality image printing at 1,600 dpi. In order to achieve this nozzle density, the nozzles are fabricated by integrating MEMS-CMOS technology and in this context reference may be made to International Patent Application No. PCT/AU00/00338 lodged by the present applicant and entitled "Thermal Actuator".
These high speed page width ink jet printers produce an image on a sheet by causing an actuator arm to move relative to a substrate by forming the actuating arm in part from an electrically resistive material and by applying a current to the arm to effect movement of the arm. The arm is connected to a paddle so that upon movement of the arm the paddle is moved to eject a droplet of ink onto the sheet. In order to eject the droplet of ink the paddle extends into a nozzle chamber which has a nozzle aperture and movement of the paddle causes the droplet to be ejected from the nozzle aperture. It is therefore necessary for the actuator arm and the paddle to move relative to the nozzle chamber in order to effect ejection of the droplet. Also, in view of the need for the actuator arm and paddle to move relative to the nozzle chamber, there is also a need to seal the nozzle chamber where the actuator arm enters the chamber so the ink does not spuriously leak from the chamber during operation of the printer.